The invention relates to firearms, in particular to designs of automatic small arms. 5.45 mm Kalashnikov assault rifle is known (see V. I. Murakhovsky, E. A. Slutskly. xe2x80x9cSpecial Purpose Weaponsxe2x80x9d Moscow 1995 p.44).
The assault rifle can fire by single shots or continuously; the burst length is determined by the shooter.
The assault rifle features the following shortcomings:
low effectiveness of fire because of high bullet dispersion.
High bullet dispersion is the result of the following factors:
the recoil pulse after each slot is transferred to the shooter via the receiver and the butt thus displacing the xe2x80x9cshooter-weaponxe2x80x9d system in space. In this process the assault rifle moves backward and sidewise dispersing the bullet trajectory;
parts of the assault rifle (the bolt, the bolt support) which move within the receiver and impact the receiver walls in the forward and backward positions create continuous disturbances which change the position of the weapon in space;
when the rate of continuous fire is low the xe2x80x9cshooter-weaponxe2x80x9d system travels considerably which increases bullet dispersion.
The shooter who determines the number of shots in the burst by himself can make from 2 to 5 shots in the burst. Due to large deflection of the assault rifle between the shots the bullets of last shots (3, 4, 5) fly far aside from the target and reduce the efficiency of the weapon.
The rate of fire of the assault rifle described in not high enough because of low coefficient of counter floor restoration under hard impact of moving parts against the butt plate.
Also a Czech heavy machine gun ZB-53 is known (xe2x80x9cMateriel of Small Arms, Book Two, Edited by A. A. Blagonravovxe2x80x9d, OBORONGIZ NKAP, Moscow 1946, pp.374-395
(Prototype).
The machinegun relates to the types of automatic weapon with removal of powder gases. In ZB-53 machinegun the coupled barrel and receiver are shock-proof and in the process of firing they recoil backward compressing the return spring. The lock comprises the bolt and the bolt support with a retracting mechanism and a buffer device.
The trigger mechanism allows for single shot and continuous fire. The cartridges are fed from a metal hinged belt by a feed arm.
The machinegun has two rates of fire which can be changed by a gas-removing regulator and switching on and off of the buffer device of the bolt support.
The gas-removing engine comprises a gas tube support with a gas chamber, gas-removing regulator, gas escape hole in the walls of the barrel, radiator and connection pipe.
In the firing pin mechanism the role of the firing hammer is performed by the lug of the bolt support interacting with the firing pin.
Shortcoming of ZB-53 machine gun:
1. large weight;
2. low effectiveness of fire.
The reasons of low effectiveness of fire are the same as for AK-74 assault rifle and similar weapon in which the recoil pulse and the co-impact of moving parts after each shot are transferred to the shooter or to the carrier which results in deflection of the weapon sidewise from the target after each shot and in bullet dispersion.
Besides, the machinegun cannot fire by short bursts of 2-3 shots, and at the 4-th and each next shot in the burst the weapon deflects sidewise from the target and disperses the bullet trajectory.
The object of the claimed invention is to solve the problem of dispersion reduction when firing by bursts. The problem can be solved by special design of the trigger and firing mechanism which provides changeable rate of burst fire as well as by introduction of a device of angular displacement of the barrel assembly relatively the housing which results in reduction of deflection of the weapon in space in the process of firing.
The essence of the invention is expressed in the following combination of essential features enough to gain the technical results provided by the invention.
The automatic weapon comprises a barrel assembly spring-mounted in the housing with the possibility of movement, a gas-removing engine, a bolt support with the bolt, a buffer mechanism, a feeding mechanism, a device to feed the cartridges into the cartridge chamber, a firing pin mechanism and a trigger mechanism.
The claimed invention differs from the nearest prototype in the following features:
the firing pin mechanism has a firing hammer which can move along the axle of the weapon and which is installed in the receiver in such a way that it can interact with the bolt support;
the trigger mechanism is made in the form of a firing trigger, a tripper with cam plates and a sear with a pawl; the firing trigger is made in such a way that it can interact with the tripper;
the tripper is installed in the housing and can move;
the cam plates of the tripper are designed to interact with the spring-mounted sear pawl which can interact with the firing hammer.
Besides, the automatic weapon is equipped with a device of angular displacement of the barrel assembly relatively the housing.
The device of angular displacement is made in the form of a guiding element and a support base interacting with the guiding element; the support base can be installed on the housing or on the barrel assembly and the guiding element can be installed on the barrel assembly or on the housing respectively.
Along with this the feeding mechanism is made in the form of a magazine placed on the housing.
The device of feeding cartridges into the cartridge chamber comprises an intermediate chamber and a follower kinematically connected with the bolt support.
The intermediate chamber is made in the receiver stationary or formed by the walls of the receiver and the housing.
The barrel in the area of the gas remover is made in the form of at least one blind slot between the layers of the barrel and gas-escape holes connecting the blind slot with the bore and the chamber of the gas-removing engine.
The bolt support has a slotted plate which projects beyond the back end; the firing hammer is made with a cam surface for interaction with the sear and features a lug.
The tripper is installed in such a way that it can turn on the axle located along the weapon.
The tripper is installed in such a way that it can reciprocate along its turning axle; it is connected with the selector lever and in the housing there is a slot with a fixing recess for the selector lever.
The buffer mechanism is equipped with a stop; in the bolt support there is a hole for the stop; the length of the stop equals to the maximum distance between the supporting surfaces of the bolt and the bolt support.
The muzzle attachment device features a bullet hole, an expanding and a releasing chambers.
The muzzle attachment device is equipped with a second expanding chamber. The cavities of the expanding chambers can be made intercrossed with opposite eccentricity relative to the bullet hole.
The cavities of expanding chambers are made with displacement against each other in the transversal and longitudinal directions and relative to the bullet hole.
The sighting system comprises a travelling front sight and a backsight.
The backsight has two vertical seats for light elements, and the front sight has one horizontal seat.
The backsight is made in the form of a lobed disk with sighting holes.
The sighting system comprises the base of the optical sight.
The housing is made of plastic and the base of the optical sight serves as reinforcing element and is made with longitudinal guiding slots for reciprocal lugs of the receiver.